Recently, as a new memory device, a semiconductor memory device called Resistance Random Access Memory (RRAM) is noted. The RRAM uses a resistance memory element which has a plurality of resistance states of different resistance values, which are changed by electric stimulations applied from the outside and whose high resistance state and low resistance state are corresponded to, e.g., information “0” and “1” to be used as a memory element. The RRAM highly potentially has high speed, large capacities, low electric power consumption, etc. and is considered prospective.
The resistance memory element has a resistance memory material whose resistance states are changed by the application of voltages sandwiched between a pair of electrodes. As the typical resistance memory material, oxide materials containing transition metals are known.
The semiconductor memory device using the resistance memory element is disclosed in, e.g., U.S. Pat. No. 6,473,332, A. Beck et al., Appl. Phys. Lett., Vol. 77, p. 139 (2000), W. W. Zhuang et al., Tech. Digest IEDM 2002, p. 193, and I. G. Baek et al., Tech. Digest IEDM 2004, p. 587.
Dynamic Random Access Memory (DRAM) and Static Random Access Memory (SRAM), and Ferroelectric Random Access Memory (ReRAM), which is prospective as a nonvolatile RAM of the next generation, etc. must have areas of above a certain size so as to ensure a difference required for a reading between before and after a rewriting of data, which is one factor blocking their higher integration. Magnetoresistive Random Access Memory (MRAM) has larger current values necessary for the magnetization inversion as the element area is decreased, which limits the cell size in relation with the writing current value, etc. In view of them, nonvolatile memory materials which facilitate the integration increase and a nonvolatile memory device using such nonvolatile memory materials have been required.